Methods of fabricating camera module and spacer of a lens structure in the camera module

ABSTRACT

A camera module and a fabrication method thereof are provided. The camera module includes a lens structure and an image sensor device chip disposed under the lens structure. The lens structure includes a transparent substrate and a lens disposed on the transparent substrate. A spacer is disposed on the transparent substrate to surround the lens, wherein the spacer contains a base pattern and a dry film photoresist. The method includes forming a base pattern on a carrier and attaching a dry film photoresist on the carrier. The dry film photoresist is planarized by a lamination process and then patterned to form a spacer. A transparent substrate having a plurality of lenses is provided. The spacer is stripped from the carrier, attaching on the transparent substrate to surround each of the lenses, and then bonded with image sensor device chips.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of pending U.S. patent application Ser.No. 13/152,690, filed Jun. 3, 2011 and entitled “CAMERA MODULE ANDSPACER OF A LENS STRUCTURE IN THE CAMERA MODULE”, the entirety of whichis incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a camera module and more particularly to aspacer of a lens structure in the camera module and a method forfabricating the spacer, and the height of the spacer is adjustableaccording to the fabrication method.

2. Description of the Related Art

In conventional camera modules, a lens structure is disposed over animage sensor device. The lens structure comprises a lens for adjustmentof incident light, so that the image sensor device can capture an imagemore effectively. Moreover, the lens structure further comprises aspacer surrounding the lens to control a distance between the lens andthe image sensor device for optimum optical performance of the cameramodules.

In a conventional method, the spacer is fabricated by drilling a glasssubstrate. Because the thickness of the glass substrate is fixed, thethickness of the spacer formed by drilling the glass substrate cannot beadjusted. In another conventional method, the spacer is fabricated byexposing and developing a photoresist. Because the thickness of thephotoresist is fixed, the thickness of the spacer formed by exposing anddeveloping the photoresist cannot be adjusted. Thus, the thickness ofthe spacer fabricated by the conventional method cannot be adjusted foroptimum optical performance of camera modules.

Therefore, a camera module capable of overcoming the above problems toform a spacer having an adjustable height is desired.

BRIEF SUMMARY OF THE INVENTION

A camera module and a method for fabricating a camera module areprovided, wherein a height of a spacer of a lens structure of the cameramodule is adjustable through a volume of a base pattern in the spacer, apattern density of the base pattern and a thickness of a dry filmphotoresist in the spacer.

An exemplary embodiment of the camera module comprises a lens structureand an image sensor device chip disposed under the lens structure. Thelens structure includes a transparent substrate having a first surfaceand a second surface opposite to the first surface. A lens is disposedon the first surface of the transparent substrate. A spacer is disposedon the first surface of the transparent substrate to surround the lens,wherein the spacer contains a base pattern and a dry film photoresist.

In an exemplary embodiment, a method for fabricating a camera module isprovided. The method comprises providing a carrier and forming a basepattern on the carrier. A dry film photoresist is attached on thecarrier and the base pattern. A lamination process is performed toplanarize the dry film photoresist. Then, the dry film photoresist ispatterned to form a spacer. A transparent substrate having a pluralityof lenses is provided. The spacer is stripped from the carrier and thenthe spacer is attached on the transparent substrate to surround each ofthe lenses. Then, a plurality of image sensor device chips is bondedunder the lenses.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 shows a schematic plane view of a lens structure for a cameramodule according to an embodiment of the invention;

FIG. 2 shows a schematic plane view of a lens structure for a cameramodule according to an embodiment of the invention;

FIG. 3 shows a schematic plane view of a lens structure for a cameramodule according to an embodiment of the invention;

FIG. 4 shows a schematic cross section of a camera module along a dottedline 4-4′ of FIG. 3 according to an embodiment of the invention;

FIGS. 5A-5F show cross sections of intermediate stages of fabricating alens structure according to an embodiment of the invention; and

FIGS. 6A-6G show cross sections of intermediate stages of fabricating alens structure according to an embodiment of the invention.

DETAILED DESCRIPTION OF INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

An exemplary embodiment of the invention provides a lens structure for acamera module, wherein the lens structure includes a spacer having anadjustable height. FIG. 1 shows a plane view of a lens structure 200 fora camera module according to an embodiment of the invention. A basepattern 102 is disposed on a transparent substrate 100, for example aglass substrate. The base pattern 102 includes a plurality ofrectangular rings which are connected with each other. A dry filmphotoresist 104 is disposed on the transparent substrate 100 and coversthe base pattern 102. The dry film photoresist 104 is patterned to havea plurality of openings 106 to expose portions of the transparentsubstrate 100. The base pattern 102 and the dry film photoresist 104 arecombined to form a spacer of the lens structure 200. A plurality oflenses 108 is disposed on the transparent substrate 100. Each of thelenses 108 is disposed in each of the openings 106 and is surrounded bythe spacer of the lens structure 200. The shape of the lens 108, theopening 106 and the rectangular ring of the base pattern 102 areconcentric.

Today's trend in camera-equipped products demands miniaturization;therefore, it requires dry film photoresist to replace the glass in thespacer manufacturing for size reduction. Dry film photoresist is aphotosensitizing material used in photolithography to form precisionpatterns and provides excellent conformity that allows lamination for amultilayer configuration with the desired thickness. The seamlessinterfaces between dry film photoresist layers can be achieved byselecting dry film formulation with superior adhesion and applyingproper manufacturing processes.

If dry film photoresist is processed below 75 degree Celsius for thesteps of lamination, exposure, development, and so forth, the dry filmphotoresist stays wherever it is placed instead of entering anyunprotected, unenclosed, or unoccupied space. That is, dry filmphotoresist below this temperature is not able to flow. Consequently,solvents can easily strip the dry film photoresist afterwards; noresidue will be left in any unprotected, unenclosed, or unoccupiedspace. On the contrary, dry film photoresist processed above 75 degreeCelsius will refer to certain of the movement characteristic of fluids.Cure or a curing process is applied afterwards to the moved anddistributed dry film photoresist and the cured dry film photoresist willbe hardened but not be removed by solvents.

In the embodiment of the invention, the dry film photoresist 104 has amovement characteristic at a temperature of above 75° C. of a laminationprocess. During the lamination process, the dry film pattern 104 isplanarized. Thus, an increasing thickness of the dry film photoresist104 on the base pattern 102 is determined by a volume of the basepattern 102, a pattern density of the base pattern 102 and an originalthickness of the dry film pattern 104 before the lamination process.When the volume of the base pattern 102 is increased, the height of thespacer is increased. When the pattern density of the base pattern 102 isincreased, the height of the spacer is increased. When the originalthickness of the dry film pattern 104 is increased, the height of thespacer is increased.

Thus, according to the embodiment of the invention, a height of thespacer which is formed from the base pattern 102 and the dry filmphotoresist 104 is adjustable before a UV curing process is performed tothe spacer. In order to adjust the height of the spacer, a special basepattern 102 is used for adjusting the thickness of the dry filmphotoresist 104 on the special base pattern 102 during the laminationprocess. Accordingly, the embodiments of the invention provide spacershaving various heights for lens structures of a camera module and theheights of the spacers can be fine adjusted by the design of the basepattern to achieve optimum optical performance for the camera modules.

In an exemplary example, referring to FIG. 1, the base pattern 102 hasan outside length L1 of about 4320 μm and an inside length L2 of about4098 μm. A thickness of the base pattern 102 is about 50 μm and anoriginal thickness of the dry film photoresist 104 is about 100 μm.After a lamination process, an increased thickness of the dry filmphotoresist 104 on the base pattern 102 is about 5 μm. In anotherexemplary example, referring to FIG. 1 again, the base pattern 102 hasan outside length L1 of about 4320 μm and an inside length L2 of about3864 μm. A thickness of the base pattern 102 is about 50 μm and anoriginal thickness of the material layer of the dry film photoresist 104is about 100 μm. After a lamination process, an increased thickness ofthe dry film photoresist 104 on the base pattern 102 is about 10 μm.Thus, according to an embodiment of the invention, the increasedthickness of the dry film photoresist 104 on the base pattern 102 can beadjusted through changing of the inside length of the base pattern 102.Further, according to the embodiments of the invention, the height ofthe spacer of the lens structure can be fine adjusted through the designof the base pattern.

FIG. 2 shows a plane view of a lens structure 200 for a camera moduleaccording to an embodiment of the invention, wherein the base pattern102 includes a plurality of rectangular rings which are separated fromeach other. The shape of each of the lenses 108, each of the openings106 of the dry film photoresist 104 and each of the rectangular rings ofthe base pattern 102 are concentric. The base pattern 102 and the dryfilm photoresist 104 are combined to form a spacer of the lens structure200. Similarly, a height of the spacer of the lens structure 200 isadjustable before performing a UV curing process on the dry filmphotoresist 104. Thus, the height of the spacer of the lens structure200 can be adjusted by the design of the base pattern 104 to achieveoptimum optical performance for the camera module.

FIG. 3 shows a plane view of a lens structure 200 for a camera moduleaccording to an embodiment of the invention, wherein the base pattern102 includes a plurality of circular rings which are separated from eachother. Each of the lenses 108, each of the openings 106 of the dry filmphotoresist 104 and the shape of each of the circular rings of the basepattern 102 are concentric. The base pattern 102 and the dry filmphotoresist 104 are combined to form a spacer of the lens structure 200.Because the dry film photoresist 104 has a planarized property during alamination process, a height of the spacer of the lens structure 200 isadjustable before performing a UV curing process on the dry filmphotoresist 104. Thus, the height of the spacer of the lens structure200 can be adjusted by the design of the base pattern 104 to achieveoptimum optical performance for the camera module.

FIG. 4 shows a cross section of a camera module 300 along a dotted line4-4′ of FIG. 3 according to an embodiment of the invention. The cameramodule 300 includes four lens structures 200 a, 200 b, 200 c and 200 ddisposed over an image sensor device chip 112 that is formed on asemiconductor substrate 110, such as a wafer. Although the camera module300 of FIG. 4 is illustrated with four lens structures, other amounts oflens structures can also be used for the camera module 300. The firstlens structure 200 a includes a spacer 107 disposed on a bottom surface100B of a first transparent substrate 100 a and a lens 108 a surroundedby the spacer 107. The spacer 107 is formed from a base pattern 102 aand a dry film photoresist 104 a. The spacer 107 has an opening 106 aand the lens 108 a is disposed in the opening 106 a.

The second lens structure 200 b includes a spacer 104 b disposed on anupper surface 100A of the first transparent substrate 100 a and a lens108 b surrounded by the spacer 104 b. The spacer 104 b is formed from adry film photoresist. The spacer 104 b has an opening 106 b and the lens108 b is disposed in the opening 106 b.

The third lens structure 200 c includes a spacer 107 disposed on abottom surface 100B of a second transparent substrate 100 b and a lens108 c surrounded by the spacer 107. The spacer 107 of the third lensstructure 200 c is formed from a base pattern 102 c and a dry filmphotoresist 104 c. The spacer 107 has an opening 106 c and the lens 108c is disposed in the opening 106 c.

The fourth lens structure 200 d includes a spacer 107 disposed on anupper surface 100A of the second transparent substrate 100 b and a lens108 d surrounded by the spacer 109. The spacer 109 is formed from a basepattern 102 d and a dry film photoresist 104 d. The spacer 109 has anopening 106 d and the lens 108 d is disposed in the opening 106 d. Inthe spacer 109 of the fourth lens structure 200 d, the base pattern 102d is embedded in the spacer 109.

The four lens structures 200 a, 200 b, 200 c and 200 d are bondedtogether to form a lens element, and then the lens element is bondedwith the semiconductor substrate 110 which has the image sensor devicechip 112 formed thereon. Although the camera module 300 of FIG. 4 showsone image sensor device chip 112 and each lens structure shows one lens,the lens element can be fabricated at a wafer level scale process andbonded with a wafer having a plurality of image sensor device chipsthereon. Then, the lens element and the wafer are diced to separate theimage sensor device chips 112 to form the camera module 300 as shown inFIG. 4.

According to the embodiments of the invention, the base pattern can beused in the spacer of any of the lens structures to adjust the height ofthe spacer for various lenses. Although the base pattern and the dryfilm photoresist have fixed original thicknesses, the final height ofthe spacer formed from the base pattern and the dry film photoresist canbe fine adjusted by the design of the base pattern, such as a volume ofthe base pattern, a pattern density of the base pattern on a carrier anda thickness of the dry film photoresist.

FIGS. 5A-5F show cross sections of intermediate stages of fabricating alens structure 200 a or 200 c according to an embodiment of theinvention. Referring to FIG. 5A, a carrier 120 is provided. The carrier120 is for example a polymer film and a formed spacer can be strippedfrom the carrier 120,. A material layer (not shown) of the base pattern102, for example a dry film type photoresist is disposed on the carrier120. Then, the material layer is patterned by an exposure and adevelopment process to form the base pattern 102 on the carrier 120.

Referring to FIG. 5B, a dry film photoresist 103 is attached on the basepattern 102 and the carrier 120. In an embodiment, the material of thedry film photoresist 103 may be the same as that of the base pattern102. In another embodiment, the material of the dry film photoresist 103may be different from the material of the base pattern 102.

Referring to FIG. 5B and 5C, the dry film photoresist 103 is planarizedby a lamination process. An exposed surface F of the carrier 110 for thelamination of the dry film photoresist 103 is shown in FIG. 5B, which isnot occupied by the base pattern 102.

Referring to FIG. 5D, after the lamination process, the dry filmphotoresist 103 is patterned by an exposure and a development process toform a dry film photoresist pattern 104 having an opening. The dry filmphotoresist pattern 104 covers the sidewalls and the top surface of thebase pattern 102. The base pattern 102 and the dry film photoresistpattern 104 are combined to form a spacer 107 of the lens structure,wherein the height of the spacer 107 is adjustable.

Referring to FIG. 5E, a transparent substrate 100, for example a glasssubstrate is provided. A lens 108 is formed on a surface 100A of thetransparent substrate 100. Referring to FIG. 5D and FIG. 5F, the spacer107 is stripped from the carrier 120 and then the spacer 107 is attachedonto the surface 100A of the transparent substrate 100 to surround thelens 108 and form the lens structure 200 a or 200 c as shown in FIG. 4.

Further, another lens (not shown) may be formed on another surface 100Bof the transparent substrate 100, and then another spacer (not shown)may be attached onto the surface 100B of the transparent substrate 100to surround the lens to form another lens structure, for example thelens structure 200 b or 200 d as shown in FIG. 4.

FIGS. 6A-6G show cross sections of intermediate stages of fabricating alens structure 200 d according to an embodiment of the invention.Referring to FIG. 6A, a carrier 120, for example a polymer film, isprovided. A formed spacer can be stripped from the carrier 120. A dryfilm photoresist 101 is disposed on the carrier 120.

Referring to FIG. 6B, a material layer (not shown) of the base pattern102 is disposed on the dry film photoresist 101. Then, the materiallayer of the base pattern 102 is patterned by an exposure and adevelopment process to form the base pattern 102 on the dry filmphotoresist 101.

Referring to FIG. 6C, a dry film photoresist 103 is attached on the basepattern 102 and the dry film photoresist 101. In an embodiment, thematerial of the dry film photoresist 101, the material of the basepattern 102 and the material of the dry film photoresist 103 may be thesame. In another embodiment, the material of the dry film photoresist101, the material of the base pattern 102 and the material of the dryfilm photoresist 103 may be different form each other. In otherembodiments, the material of the dry film photoresist 101 may be thesame as the material of the dry film photoresist 103 and different fromthe material of the base pattern 102.

Referring to FIG. 6C and 6D, the dry film photoresist 103 is planarizedby a lamination process. An exposed surface F of the dry filmphotoresist 101 for the lamination of the dry film photoresist 103 isshown in FIG. 6B.

Referring to FIG. 6E, after the lamination process, the dry filmphotoresist 103 and the dry film photoresist 101 are patterned by anexposure and a development process to form a dry film photoresistpattern 104 and a dry film photoresist pattern 105 which have an opening106 therein. The dry film photoresist pattern 104 covers the sidewallsand the top surface of the base pattern 102. The dry film photoresistpattern 105 is disposed under the base pattern 102. The dry filmphotoresist patterns 104 and 105 and the base pattern 102 are combinedto form a spacer 109 of the lens structure 200 d as shown in FIG. 4,wherein the height of the spacer 109 is adjustable. The base pattern 102is embedded in the spacer 109.

Referring to FIG. 6F, a transparent substrate 100, for example a glasssubstrate is provided. A lens 108 is formed on a surface 100A of thetransparent substrate 100. Referring to FIG. 6E and FIG. 6G, the spacer109 is stripped from the carrier 120 and then the spacer 109 is attachedonto the surface 100A of the transparent substrate 100 to surround thelens 108 to form the lens structure 200 d as shown in FIG. 4.

Moreover, before forming the lens structure 200 d, another lensstructure, for example the lens structure 200 c as shown in FIG. 4 maybe formed on another surface 100B of the transparent substrate 100.

In the embodiments of the invention, the spacer containing a basepattern therein may be disposed in a lens structure, for example thelens structure 200 c of FIG. 4, which is bonded with another lensstructure, for example the lens structure 200 b of FIG. 4. Also, thespacer with a base pattern therein may be disposed in a lens structure,for example the lens structure 200 a of FIG. 4, which is bonded with animage sensor device chip, for example the image sensor device chip 112of FIG. 4.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A method for fabricating a camera module,comprising: providing a first carrier; forming a first base pattern onthe first carrier; attaching a first dry film photoresist on the firstcarrier and the first base pattern; performing a lamination process toplanarize the first dry film photoresist; patterning the first dry filmphotoresist to form a first spacer; providing a first transparentsubstrate having a plurality of first lenses formed on a first surfaceof the first transparent substrate; stripping the first spacer from thefirst carrier; attaching the first spacer on the first surface of thefirst transparent substrate to surround each of the first lenses to forma first lens structure; and bonding a plurality of image sensor devicechips.
 2. The method as claimed in claim 1, wherein the first basepattern comprises a plurality of rectangular rings, and the plurality ofrectangular rings are connected with each other or separated from eachother.
 3. The method as claimed in claim 2, wherein the first basepattern comprises a plurality of circular rings, and the plurality ofcircular rings are separated from each other.
 4. The method as claimedin claim 1, wherein the step of forming the first base pattern on thefirst carrier comprises adjusting a volume of the first base pattern andadjusting a pattern density of the first base pattern.
 5. The method asclaimed in claim 1, wherein before the step of attaching the first dryfilm photoresist on the first carrier and the first base pattern,further comprises adjusting a thickness of the first dry filmphotoresist.
 6. The method as claimed in claim 1, wherein a height ofthe first spacer is adjusted by a volume of the first base pattern, apattern density of the first base pattern and a thickness of the firstdry film photoresist.
 7. The method as claimed in claim 1, furthercomprising: forming a second lens structure on a second surface of thefirst transparent substrate opposite to the first surface, and thesecond lens structure is formed above the first lens structure, whereinthe second lens structure comprises a plurality of second lenses and asecond spacer surrounding each of the second lenses, and wherein thesecond spacer includes a second dry film photoresist.
 8. The method asclaimed in claim 7, wherein the step of forming the second lensstructure comprises: providing a second carrier; forming a second basepattern on the second carrier; attaching the second dry film photoresiston the second carrier and the second base pattern; performing alamination process to planarize the second dry film photoresist;patterning the second dry film photoresist to form the second spacer;stripping the second spacer from the second carrier; and attaching thesecond spacer on the second surface of the first transparent substratehaving the plurality of second lenses to surround each of the secondlenses.
 9. The method as claimed in claim 8, wherein a height of thesecond spacer is adjusted by a volume of the second base pattern, apattern density of the second base pattern and a thickness of the seconddry film photoresist.
 10. The camera module as claimed in claim 8,wherein the second base pattern is covered with the second dry filmphotoresist.
 11. The method as claimed in claim 7, further comprising:forming a third lens structure above the second lens structure, whereinthe third lens structure comprises a plurality of third lenses formed ona third surface of a second transparent substrate, and a third spacersurrounding each of the third lenses and bonding with the second spacerof the second lens structure, and wherein the third spacer includes athird dry film photoresist.
 12. The method as claimed in claim 11,wherein the step of forming the third lens structure comprises:providing a third carrier; forming a third base pattern on the thirdcarrier; attaching the third dry film photoresist on the third carrierand the third base pattern; performing a lamination process to planarizethe third dry film photoresist; patterning the third dry filmphotoresist to form the third spacer; stripping the third spacer fromthe third carrier; and attaching the third spacer on the third surfaceof the second transparent substrate having the plurality of third lensesto surround each of the third lenses.
 13. The method as claimed in claim12, wherein a height of the third spacer is adjusted by a volume of thethird base pattern, a pattern density of the third base pattern and athickness of the third dry film photoresist.
 14. The camera module asclaimed in claim 12, wherein the third base pattern is covered with thethird dry film photoresist.
 15. The method as claimed in claim 11,further comprising: forming a fourth lens structure on a fourth surfaceof the second transparent substrate opposite to the third surface, andthe fourth lens structure is formed above the third lens structure,wherein the fourth lens structure comprises a plurality of fourth lensesformed on the fourth surface of the second transparent substrate and afourth spacer surrounding each of the fourth lenses, and wherein thefourth spacer includes a fourth dry film photoresist; and dicing theplurality of image sensor device chips, the first spacer, the secondspacer, the third spacer and the fourth spacer to separate the imagesensor device chips.
 16. The method as claimed in claim 15, wherein thestep of forming the fourth lens structure comprises: providing a fourthcarrier; forming a fourth base pattern on the fourth carrier; attachingthe fourth dry film photoresist on the fourth carrier and the fourthbase pattern; performing a lamination process to planarize the fourthdry film photoresist; attaching a fifth dry film photoresist on thefourth dry film photoresist; patterning the fifth dry film photoresistand the fourth dry film photoresist to form the fourth spacer; strippingthe fourth spacer from the fourth carrier; and attaching the fourthspacer on the fourth surface of the second transparent substrate havingthe plurality of fourth lenses to surround each of the fourth lenses.17. The method as claimed in claim 16, wherein a height of the fourthspacer is adjusted by a volume of the fourth base pattern, a patterndensity of the fourth base pattern, a thickness of the fourth dry filmphotoresist and a thickness of the fifth dry film photoresist.
 18. Themethod as claimed in claim 16, wherein the fourth base pattern isembedded in the fourth dry film photoresist and the fifth dry filmphotoresist.
 19. The method as claimed in claim 16, wherein each of thefirst lenses does not connect to the first spacer, each of the secondlenses does not connect to the second spacer, each of the third lensesdoes not connect to the third spacer, and each of the fourth lenses doesnot connect to the fourth spacer.